Ignition timing control method and system
AssigneeNissan Motor Co., Ltd.
InventorHiroshi Yamaguchi
Life of this patent
Estimating the term…
Abstract
An ignition timing control for an internal combustion engine is performed by measuring engine operating variables to estimate the engine operating conditions and determining an optimal ignition timing depending upon the measured engine operating variables. The thus determined ignition timing is subject to two limitations to limit the amount of ignition timing change to be within a predetermined range, thereby to prevent an abrupt change of ignition timing even when the engine operating conditions change from one state to another. The ignition timing may be further limited to limit the amount of ignition timing change toward a spark advance during an initial period of acceleration.
Claims11
A method of controlling ignition timing of an internal combustion engine, said method comprising iterations of the steps of:
- (a) measuring engine operating variables to estimate the engine operating conditions,
- (b) determining an optimal ignition timing, as a basic value, depending on the engine operating variables measured in said measuring step,
- (c) storing an ignition timing, used in a previous iteration of the method, as a previous value,
- (d) comparing said basic value with said previous value to find a difference therebetween,
- (e) determining if said difference is greater than a first predetermined range,
- (f) performing a first limiting step of limiting said basic value, if said difference is beyond said first predetermined range, to a value selected so that said difference is kept within said first predetermined range,
- (g) performing a second limiting step of further limiting said basic value, if said difference is beyond a second predetermined range which is narrower than said first predetermined range, thereby limiting the amount of ignition timing change toward a spark advance in such a manner that said difference is kept within said second predetermined range during a limited time interval from a position change of a throttle valve for the engine from its fully closed position to an open position,
- (h) setting an ignition timing to be used during a present application of the method at said basic value as limited in said first limiting step and in said second limiting step, and
- (i) executing engine ignition in accordance with the ignition timing set in said setting step.
A system for controlling ignition timing for an internal combustion engine, said system comprising:
- (a) a plurality of sensors for measuring engine operating variables to estimate engine operating conditions,
- (b) an electronic control unit arranged to receive output signals from said sensors and to determine the ignition timing depending on the engine operating conditions, said control unit comprising:
- means for determining an optimal ignition timing, as a basic value, depending on the engine operating variables measured by said sensors,
- means for storing an ignition timing, used in a previous operation of the control unit, as a previous value,
- means for comparing said basic value with said previous value to find a difference therebetween,
- first limiting means for limiting said basic value, if said difference is beyond a first predetermined range, to limit the amount of ignition timing change in such a manner that said difference is kept within said first predetermined range,
- second limiting means for limiting said basic value, if said difference is beyond a second predetermined range which is narrower than said first predetermined range, thereby to limit the amount of ignition timing change toward a spark advance in such a manner that said difference is kept within said second predetermined range during a limited time interval from a position change of a throttle valve for the engine from its fully closed position to its open position, and
- means for setting an ignition timing to be used during a present operation of the control unit at said basic value as limited by said first and second limiting means, and
- (c) an ignition executing sustem for executing engine ignition in accordance with the ignition timing set by said control unit.
Dependencies are inferred from the claim text.